Price drop triggered exchange to liquidate many customers' leveraged positions, leaving some with thousands of dollars in losses.

Customers claim the orders weren't executed correctly and the platform was hit by technical glitches. Many are demanding refunds.

Bitfinex claims everything occurred as it should.

The incident highlights the high-risk nature of the unregulated and volatile cryptocurrency space.

A "flash crash" on the world's biggest cryptocurrency exchange has left customers demanding answers and refunds, with many claiming to have lost thousands of dollars.

The price of cryptocurrencies NEO, OMG, and ETP crashed as much as 90% in minutes on the Bitfinex exchange on Wednesday before quickly bouncing back to former levels.

The price crash led Bitfinex, the world's largest cryptocurrency exchange by daily volume, to close the positions of many traders who had placed leveraged bets on these digital currencies. Leveraged trading involves borrowing money to increase exposure. It can lead to outsized gains compared to how much you deposit, but also outsized losses.

Customers have taken to Twitter, Reddit, Medium, and messaging app Telegram to protest Bitfinex's treatment of those who use margin trading on the platform.

They claim that Bitfinex's platform was hit by delays and technical issues at the time of the "flash crash," leaving many powerless to respond. Traders are also upset that the crash only appeared to happen on Bitfinex and are suspicious of what caused it. And many say stop losses — automated sell orders meant to activate once an asset price reaches a certain floor and therefore limit losses — were executed at prices well below those set by users.

Bitfinex argues that it was functioning as normal and the company's terms of service include provisions to close out positions once leverage ratios fall below 15%. The company puts the "flash crash" down to the volatility of cryptocurrency markets.

The spat highlights the high-risk nature of cryptocurrencies, which have attracted huge interest and ballooned to more than $300 billion in 2017 but are subject to wild price swings and are largely unregulated. It also comes at a time when British Virgin Island-registered Bitfinex, which had trading volumes of $54 billion last month, is facing increasing public scrutiny.

'Panic across multiple markets'

Brett Kruger, a Bitfinex user affected by the "flash crash", told Business Insider he is unhappy with Bitfinex because he claims the website was "lagging, unresponsive" at the time of the crash. He said he was also repeatedly logged out of the website, blaming recent DDoS attacks. Bitfinex announced last Sunday that it had been hit by a distributed denial of service (DDoS) attack, a malicious attack meant to bring down the service.

Kruger said: "All of this is very time consuming for a person that called a long in a margin trade, is watching the market drop, and is trying to get out to take minimal losses." He estimates he lost $10,000 in the crash.

"If the market does indeed crash like this, should there not be given a time before the user gets liquidated? Especially if the system is unstable, laggy and unresponsive," he said. "A 15-minute max 90% drop to a 90% pump should certainly not liquidate a person. If the price has been at the 90% low for 30 minute — sure I can understand that. But this is another prevention method which could have been in place." The flash crash in the price of NEO on the Bitfinex exchange. Screenshot

In most regulated markets stop-losses are triggered as soon as a certain level is breached, regardless of how long the level is breached for. However, some traders claim that the activation of their stop-losses appears to have lagged, triggering only after the price had recovered.

A spokesperson for Bitfinex told Business Insider in an email: "On November 29, 2017, we saw similar movements across multiple markets. This was not a sudden drop in a single market; it was a panic across multiple markets."

"In a situation like this, we must liquidate customers' peer-to-peer financed positions. If we do not, there is a serious risk of a large group of financed traders losing more than can be covered by the collateral held."

One user on Telegram claims he has been left $35,000 in debt to Bitfinex after losses exceeded the deposit he had put up for margin trading.

'Warm words would not help'

Kruger wants Bitfinex to issue a public statement on the incident, refund users who were hit by the incident, and calls for "a statement on what measures are going to be taken to prevent something like this" in future.

Markus Weismann claims he lost close to $3,000 in the crash. Markus Weismann "Warm words would not help," Markus Weissmann, a Bitfinex customer from Munich, told BI. "They should refund like other exchanges did in the past, for example at the Ethereum flash crash."

Weissmann estimates he lost close to $3,000 in the crash. One Bitfinex customer who contacted Business Insider but wanted to remain anonymous claimed they lost $50,000 in the flash crash and said they have been left "devastated by it."

The Bitfinex spokesperson said: "When the loss of a position causes the leverage ratio to become lower than 15%, the platform will liquidate positions. This is clearly disclosed in our terms of service. This may result in all collateral held in an account being used to cover losses incurred. During volatile markets, slippage can be substantial."

'Trading is a 0-sum game'

An email from a Bitfinex support employee that was sent to multiple users and seen by Business Insider puts it in blunter terms.

"Trading is a 0-sum game," the email reads. "We cannot start compensating users who trade leveraged positions and see their position liquidated. If we would [sic], we would soon have every user that gets liquidated request a compensation and users would start to trade at maximum leverage all the time.

"If we take this route, we would soon be forced to start socializing losses to our funding providers as losses would be realized and someone will need to pay for them."

Brian, a Bitfinex customer from South Africa who asked Business Insider not to use his second name, said: "Nobody is asking them to socialize losses, people are asking for a platform that works, and liquidates positions at the correct time."

Brian pointed to screenshots sent to BI that he claimed showed his positions were not liquidated at the correct levels. He said he is now in debt to Bitfinex to the tune of $38,000. (Big price swings in margin trading can leave customers owing more than they deposit.)

The Bitfinex email that the stop-loss level is "not a guaranteed price a user will see his position liquidated at, but rather an indicative price of when a liquidation is triggered.

"Depending on the state of the orderbook, the liquidation order gets executed against bids or asks available in the orderbook at the time the liquidation order gets inserted. If orderbooks are thin, slippage is expected to occur."

The spokesperson for Bitfinex told BI: "All indications are at this time that positions were liquidated as they should be. To start compensating users trading on financed positions who get liquidated introduces moral hazard into the market which is unfair."

'A volatile space'

Regardless of refunds, customers want answers on what triggered the huge price crashes. Sam Aiken wrote in a Medium post: "These kinds of dumps can easily happen on small exchanges for small cryptos, but not on the biggest exchange with a few billions of daily trading volume.

"According to some theories, it was a planned hackers + whales attack." (Whales are traders with large accounts and have enough financial firepower to move markets with their orders.)

Brett Kruger believes Bitfinex's platform should have been better. Brett Kruger Asked whether there was any suspicion surrounding the crash, the spokesperson for Bitfinex told BI: "Market movements are part of what regularly happens in markets. We would note that some of our competitors went offline yesterday, offering their customers no chance to reassess positions or exposures."

Digital currencies "have experienced significant price volatility in the past year which, in combination with leverage, places you at risk of suffering significant losses and potentially losing more than you have invested," the FCA said.

Kruger told BI: "I think every margin trader understands the risk involved, but because of these risks we expect the platform that we trade on to be fail-safe and also protect the user trading there, as in the end without us where would they get their money from?

"It is the user who chooses to take those risks and, in return for the risks and 'buyers beware' we take, we expect fair play and a system that is stable 100% of the time! When unstable times arise they should freeze margin trades in the case of something like this can happen."

'We are sorry you lost money'

It is not clear how many people have been affected by the "flash crash." A group set up on messaging app Telegram for those affected has attracted 75 members in less than two days. Multiple threads about the "flash crash" problems have also appeared on Reddit and many people have taken to Twitter to complain.

Bitfinex's email to customers said: "We do understand that you are completely overwhelmed by what happened. And we are sorry you lost money. I wish we could bring you better news."

The article said that British Virgin Islands-registered Bitfinex has "been fined by regulators in the United States and cut off by American banks, and it has lost millions of dollars of customer money in two separate hackings, leading critics to question whether it even has the money it claims to hold."

In response, Bitfinex has hired New York PR agency 5W. An email from the agency on Thursday acknowledged "growing pains" for Bitfinex but added: "Some questionable actors have jumped on Bitfinex's challenges and its related cryptocurrency, Tether, at every turn.

"What they fail to do is to recognize the unprecedented and shifting crypto landscape and the fact that Bitfinex abides by all existing laws and reporting requirements such as KYC/AML, and that it remains committed to becoming the most transparent crypto exchange in the industry."